When the angle of elevation of the sun is 78 degrees, a tree casts a 13 foot shadow. How tall is the tree?

61.16 ft

Step-by-step explanation:

We can think in this situation as a triangle rectangle.

where:

The height of the tree is one cathetus

The shadow of the tree is the other cathetus.

We know that the angle of elevation of the sun is 78°, an angle of elevation is measured from the ground, then the adjacent cathetus to this angle is the shadow of the tree. And the opposite cathetus will be the height of the tree.

Now we can remember the relationship:

Tg(A) = (opposite cathetus)/(adjacent cathetus)

Where:

A = 78°

Adjacent cathetus = 13ft

opposite cathetus = height of the tree = H

Then we have the equation:

Tg(78°) = H/13ft

Tg(78°)*13ft = H = 61.16 ft

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